added option --log to plot with logarithmic scale.
added option --log to plot with logarithmic scale.

yaowenqiang/mtools,rueckstiess/mtools,parkhyeonghwa/mtools,aerrami/mtools,corymintz/mtools,tomzhang/mtools,tomzhang/mtools,gormanb/mtools,devkev/mtools,devkev/mtools,aerrami/mtools,corymintz/mtools,devkev/mtools,ces0712/mtools,yaowenqiang/mtools,parkhyeonghwa/mtools,gormanb/mtools,tomzhang/mtools,ces0712/mtools,corymintz/mtools,ces0712/mtools,yaowenqiang/mtools,aerrami/mtools,parkhyeonghwa/mtools,gormanb/mtools,rueckstiess/mtools